MTC refers to a generic term of a series of technologies and combinations thereof for implementing data communication and exchange between a machine and a machine and between a machine and a man by virtue of a wireless communication technology. MTC has two meanings: the first is a machine, which is called an intelligent device in the field of intelligence; and the second is a connection between a machine and a machine, the machines being connected through a network. MTC is widely applied to, for example, intelligent measurement and remote monitoring, and makes the life of people more intelligent. Compared with conventional interpersonal communication, MTC has the advantages of numerous MTC devices, wide application range and broad market prospect.
In an existing MTC system, an MTC device communicates with a service server such as an MTC server through a 3rd Generation Partnership Project (3GPP) network and an MTC Interworking Function (MTC-IWF).
A GBA defines a generic key agreement mechanism between a terminal and a server.
After introduction of MTC devices, there are numerous MTC devices in a mobile communication system, so that it is necessary to perform management optimization on the MTC devices in groups to reduce a network load and save network resources. Moreover, these MTC devices may frequently send small data, thereby reducing efficiency of the mobile communication system. In order to efficiently utilize the network resources, it is necessary to enhance and optimize the mobile communication system according to SDT to improve SDT efficiency of the mobile communication system. Transmitting small data between an MTC device and each of an MTC-IWF and a service server through signalling is a very effective manner, may avoid allocation of user plane resources, and may also reduce utilization of radio resources. In addition, during SDT for the condition of MTC device groups, it is necessary to perform security control and management on MTC devices in groups.
At present, an SDT protocol is introduced into a method for transmitting small data between an MTC device and each of an IWF and a service server through signalling, and is deployed in the MTC device and the MTC-IWF. Any piece of data is required to pass through the MTC-IWF for exchange between the MTC device and the service server. In the method, for ensuring security of data transmission between the MTC device and the MTC-IWF, it is necessary to create a shared key between the MTC device and the MTC-IWF. An existing solution is to create a key configured to protect secure SDT in the MTC-IWF through an Authentication and Key Agreement (AKA) process in an attachment process. In such a manner, in the same attachment process, the MTC device may perform secure SDT for many times by adopting the same small data transmission protection key. Using the same SDT protection key for multiple SDT processes increases a risk of attack to the SDT protection key. In addition, during a practical Machine-to-Machine (M2M) application, an MTC device may be required to initiate SDT for different destination servers in an attachment process, and for ensuring security, SDT for these different destination servers is required to be protected by different keys. Therefore, it is necessary to create a shared key configured to protect secure SDT between the MTC device and an MTC-IWF for each SDT process during SDT of the MTC device. For the condition of an MTC device group, it is necessary to create a shared key between a group of MTC devices and the MTC-IWF during each SDT of the MTC device group. How to create a shared key configured to protect secure SDT between a group of MTC devices and an MTC-IWF for each SDT is a technical problem urgent to be solved.